Lyons (from lynx + lion), in my world, are mid-sized (20-40 kg) feliform predators. They live and hunt in groups called prydes (obviously), and are large-prey specialists. The principal prey species are ellefants, which are miniature mammoths (about an ell tall, thus the name), and deer, which range in size from below 10 kg to above 1,000 kg - to be clear, the upper limit is for the largest deer available for hunting to, not necessarily for the largest deer actually being hunted by, the lyons.

Now, would it be plausible for male lyons to have sabre-teeth and for lyonesses not to (or vice versa, but everything below refers to the stated version)? The idea only just occurred to me, and on the face of it, it seems to make quite a bit of sense. An article I read a while ago compared sabre-teeth in quadrupeds with having daggers for thumbs in a human - good for inflicting serious injuries, but mostly just in the way otherwise. Thus, a social cat in which only one sex has exaggerated teeth would seem to get the best of both worlds, in several ways.

A typical hunt could consist in one or more females chasing and/or tackling the targeted prey, with one or more males lying in ambush and/or moving in later to deliver the killing bite, for ellefants and small deer, or to inflict a number of freely bleeding wounds which will lead to the animal's demise in short order, for larger deer. Afterwards, the females could drag the carcass away if necessary, something quite impractical for the males due to the effect of lever action on the skull bones.

Practically, the simplest way to get this would be by both sexes possessing the teeth per se, but by their only growing all the way out of their "sheaths" in the males. As in the picture below, which shows the skull of a juvenile Machairodont:

However, the lever-action problem might materialize in those as well, so perhaps a more fully sexually dimorphic dentition would be necessary?

Anyway, the main reason I'm requesting feedback here is simply that I'm not aware of any parallel cases on Earth. All hunting packs seem to consist of basically identical individuals. There are, of course, differences in size and strength which make some members better suited for e.g. running and others for e.g. tackling (quite like the members of a rugby team, really), and there are probably cases in which a few individuals somehow develop a knack for a particular role, and thus play that one role in most hunts in which they participate. But the latter is always due to behavioural rather than physical specialization, and even the former is quite different from what I have in mind.

That being said, I think I have heard about hunting packs that involve representatives of two or even more different species, each with its particular task to fulfill. I can't remember the context and details at the moment, but whatever it was, if true that would arguably represent an even more extreme case of role division. But in evolutionary terms, what has to happen for either situation to come about is rather different, so again I'm not sure how applicable that is.

I'm not an expert, but it seems like this is plausible. Perhaps large teeth for males could be the result of sexual selection as well? IE females like males with large teeth more than they do males with smaller teeth, so males with larger teeth have more offspring and pass on their genes more often. Over time it leads to larger and larger teeth. As long as it doesn't impose severe penalties on the survivability of the males before they have offspring it seems plausible to me.http://en.wikipedia.org/wiki/Sexual_selection

Perhaps large teeth for males could be the result of sexual selection as well?

Yes, that's where this idea came from, actually.

Lyons are the direct descendants of lynxes. The latter are solitary and have the characteristic ruff of hair and moderately enlarged canines, only slightly larger than those of Earth's clouded leopards, which is the most "sabre-toothed" of extant cats but of course nowhere near the familiar Smilodont dimensions:

I'd much prefer to have the lyons stick with the ruff, to underline the link between the two species. So I need something else to take the place of the mane, if I want to have that sort of sexual dimorphism at all - which I do, to underline the similarity to real lions at the same time.

I don't think it would be particularly plausible to suggest that the sexual dimorphism evolved because prydes in which some individuals happened to have larger teeth than others happened to be more efficient hunters and were thus selected for - as a group, as it were. Evolution rarely seems to work at that level, or at least not as quickly as this would have needed to happen.

However, suggesting that the sex-specific dentitions arose as a product of sexual selection, and that role division in hunting is something that came later to re-purpose something already present... that is very much how evolution often seems to work, as far as I can tell.

Summary: Sexual selection is the cause, dental sexual dimorphism the effect, and the described hunting patterns are the exaptation.

IIRC female lions IRL are the ones that do the majority of the hunting. The idea of dimorphism playing a part in societal roles is definitel present in nature.

Yes, that is true.

And there are some prides which have specialized in targeting prey conventionally thought of as being outside the size range manageable by lions, such as adult hippos and even subadult and elderly elephants. In those cases, the dominant males do uncharacteristically participate in hunting, bringing their extra strength to bear in at least somewhat specialized ways. That is a first step into the direction I'm looking at.

As I said, though, I'm not aware of any closer parallels than that, in which some members of a species have an essentially different "toolkit" from the others, and in which both of those put their tools to different uses and as a result are more effective than either one would be by itself.

As I said, though, I'm not aware of any closer parallels than that, in which some members of a species have an essentially different "toolkit" from the others, and in which both of those put their tools to different uses and as a result are more effective than either one would be by itself.

Try lions "crossed" with social insects like termites. ants, etc.

FWIW some soldier termites have mouth parts modified so much that they can't even feed themselves (according to Wikipedia).